1. Field of the Invention
The present invention relates to electric current producing cells, and more particularly to such cells employing improved molybdenum sulfide cathode structures.
2. Description of the Prior Art
There has been considerable interest in recent years in developing high energy density batteries for voltaic cells. Exemplary of the developing systems is a high energy density electrochemical cell utilizing intercalation compounds of the transition metal chalcogenides as cathode-active materials and using alkali metal anodes. For example, one such cell employs a lithium anode-active material in conjunction with an MoS.sub.x (where 2 is less than x which is less than 3) as its cathode-active material. Other such prior art systems include lithium anode/titanium disulfide cathode couples as well as those containing mixtures of cathode-active material.
In general, the chalcogenide cathode-active materials are formed into the desired electrode structures by being hot pressed in a Teflon mixture with a grid-like support structure. It has been recognized that the Teflon or other binder material is necessary to maintain the structural integrity of the desired electrode configuration.
Although little development work has been done with respect to cathode systems employing chalcogenide compounds without using binder materials, there has been some development in the battery art in general concerning various structural changes to electrode fabrication. For example, U.S. Pat. No. 3,907,589 illustrates an anode structure which is enclosed within an expanded mesh of molybdenum metal to act as a current collector and to insure structural integrity of the anode-active material. Also, U.S. Pat. No. 2,985,701 is directed to the use of a porous, woven dielectric support to form a pocket enclosure for electrodeactive materials and collector plates. The woven cloth is at least partially coated or lined with metallic particles. U.S. Pat. No. 4,161,569 describes a method of making a composite electrode wherein the synthetic resin layers composed of screen, net, fabric or grids of filaments, form pockets in which the active electrode mass is disclosed in contact with the metal support or grid. This pocket structure is adapted to permit volume change of the active mass while serving as a completely stable structure in the static sense. Also, U.S. Pat. No. 4,145,806 describes electrodes which may be either positive or negative, which include a current collecting wire and an active material retaining member which may be in the form of a wire cage, porous placque or wire screen.
Notwithstanding the foregoing prior art, it is believed that it has neither been taught nor rendered obvious that particular performance advantages may be achieved by employing particular structural arrangements with molybdenum sulfide cathode-active materials. Thus, is believed that the present invention is neither taught nor rendered obvious by the prior art.